These are required when connecting a 3D printer to the ELEGOO UNO R3 ATmega328P ATMEGA16U2 Board If you've ever stumbled upon a soft brick printer like I have, you'll need these two items, and they both worked without problems the first time. It's that simple. It's like having the right tools in a box in case something goes wrong. If you are flashing your printer's firmware, you must have these two items. Otherwise, wait for them to come to your house so you can set up the printer properly. Otherwise there is not much to say about cables. They worked. They were packed pretty well, what else do we need?